Download PSY550 Research and Ingestion

PSYC550 Biological Bases
of Behavior
Research Methods
and
Ingestion
Experimental Ablation
• experimental ablation
– The removal or destruction of a portion of the brain of a
laboratory animal; presumably, the functions that can no longer
be performed are the ones the region previously controlled.
• excitotoxic lesion
– A brain lesion produced by intracerebral injection of an
excitatory amino acid, such as kainic acid.
• 6-hydroxydopamine (6HD)
– A chemical that is selectively taken up by axons and terminal
buttons of noradrenergic or dopaminergic neurons and acts as a
poison, damaging or killing them.
Experimental Ablation
• sham lesion
– A placebo procedure that duplicates all of the step of producing
a brain lesion except for the one that actually causes the brain
damage.
• stereotaxic surgery
– Brain surgery using a stereotaxic apparatus to position an
electrode or cannula in a specified position of the brain.
• bregma
– The junction of the sagittal and coronal sutures of the skull;
often used as a reference point for stereotaxic brain surgery.
Experimental Ablation
• stereotaxic atlas
– A collection of drawings of sections of the brain of a
particular animal with measurements that provide
coordinates for stereotaxic surgery.
• sterotaxic apparatus
– A device that permits a surgeon to position an electrode
or cannula into a specific part of the brain.
Experimental Ablation
• fixative
– A chemical such as formalin; used to prepare and preserve body
tissue.
• formalin
– The aqueous solution of formaldehyde gas; the most commonly
used tissue fixative.
• perfusion
– The process by which an animal’s blood is replaced by fluid such
as a saline solution or fixative in preparing the brain for
histological examination.
• microtome
– An instrument that produces very thin slices of tissues.
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Microscopy
• transmission electron microscope
– A microscope that passes a focused beam of electrons through
thin slices of tissues to reveal extremely small details.
• scanning electron microscope
– A microscope that provides three-dimensional information about
the shape of the surface of a small object by scanning the object
with a thin beam of electrons.
• confocal laser scanning microscope
– A microscope that provides high-resolution images of various
depths of thick tissue that contains fluorescent molecule by
scanning the tissue with light from a laser beam.
Visualizing
• computerized tomography (CT)
– The use of a device that employs a computer to analyze
data obtained by a scanning beam of X-rays to produce
a two-dimensional picture of a slice through the body.
• magnetic resonance imaging (MRI)
– A technique whereby the interior of the body can be
accurately imaged; involves the interaction between
radio waves and a strong magnetic field.
Computed Tomography
• CT is readily available, fast, and inexpensive
– Great for identifying hemotomas
• Iodine contrast medium can be used to enhance
visualization of vasculature (hyperdense) to
detect
– Neoplasms
– Inflammation
Contrast Agent
Magnetic Resonance
Imaging
• Expose protons in hydrogen atoms in body to a large
magnet
• Aligns protons and essentially turns the body into a
resonating magnet
• Forces the protons to spin at an angle relative to the
magnetic field, at varying frequencies
• Produces a radio frequency that can be read and
interpreted.
MRI (T2 on Right)
• FOS
Recording and
Stimulating Neural
Activity
– A protein produced in the nucleus of a neuron in
response to synaptic stimulation.
• positron emission tomography (PET)
– The use of a device that reveals the localization of a
radioactive tracer in a living brain.
Visualizing and Siphoning
• functional MRI (fMRI)
– A modification of the MRI procedure that permits the
measurement of regional metabolism in the brain.
• microdialysis
– A procedure for analyzing chemicals present in the
interstitial fluid though a small piece of tubing made of
a semipermeable membrane that is implanted in the
brain.
Genetic Methods
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Twin Studies
Adoption Studies
Targeted Mutations
Antisense Oligonucleotides
Genetic Methods
• Targeted mutation
– A mutated gene (also called a “knockout gene”)
produced in the laboratory and inserted into the
chromosomes of mice; fails to produce a functional
protein.
• Antisense Oligonucleotides
– A mutated portion of an RNA strand is inserted and
fails to produce functional protein
Ingestion!
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Physiological Regulatory
Mechanisms
• homeostasis
– The process by which the body’s substances and characteristics
(such as temperature and glucose level) are maintained at the
optimal level.
• ingestive behavior
– Eating or drinking.
• system variable
– A variable that is controlled by a regulatory mechanism, for
example, temperature in a heating system.
• set point
– The optimal value of the system variable in a regulatory
mechanism.
Drinking
• intracellular fluid
– The fluid contained within cells.
• extracellular fluid
– All body fluids outside cells; interstitial fluid, blood plasma, and
cerebrospinal fluid.
• intravascular fluid
– The fluid found within the blood vessels.
• interstitial fluid
– The fluid that bathes the cells, filling the space between the cells
of the body (the “interstices”).
Drinking
• osmometric thirst
– Thirst produced by an increase in the osmotic pressure
of the interstitial fluid relative to the intracellular fluid,
thus producing cellular dehydration.
• osmoreceptor
– A neuron that detects changes in the solute
concentration of the interstitial fluid that surrounds it.
Drinking
• OVLT (organum vasculosum of the lamina terminalis)
– A circumventricular organ located anterior to the anteroventral
portion of the third ventricle, served by fenestrated capillaries
and thus lacks a blood-brain barrier.
• subfornical organ (SFO)
– A small organ located in the confluence of the lateral ventricles,
attached to the underside of the fornix; contains neurons that
detect the presence of angiotensin in the blood and excite neural
circuits that initiate drinking.
You get thirsty when you
lose a lot of blood.
Strongly Agree
Agree
Disagree
Strongly Disagree
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Drinking
• volumetric thirst
– Thirst produced by hypovolemia.
• renin
– A hormone secreted by the kidneys that causes the
conversion of angiotensinogen in the blood into
angiotensin.
• angiotensin
– A peptide hormone that constricts blood vessels, causes
the retention of sodium and water, and produces thirst
and a salt appetite.
Drinking
• nucleus of the solitary tract
– A nucleus of the medulla that receives information
from the visceral organs and from the gustatory system.
• medial preoptic nucleus
– A small nucleus situated around the decussation of the
anterior commissure; plays a role in thirst stimulated by
angiotensin.
A “starvation diet” can
make you gain weight.
Strongly Agree
Agree
Disagree
Strongly Disagree
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Eating at the Set Point
• Glucostatic Theory
• Lipostatic Theory
• “Set Points”
– Mutable by behavior
Eating: Some Facts
About Metabolism
• fasting phase
– A phase of metabolism during which nutrients are not
available from the digestive system; glucose, amino
acids, and fatty acids are derived from glycogen, protein,
and adipose tissue during this phase.
• absorptive phase
– The phase of metabolism during which nutrients are
absorbed from the digestive system; glucose and amino
acids constitute the principal source of energy for cells
during this phase, and excess nutrients are stored in
adipose tissue in the form of triglycerides.
What Starts a Meal?
• ghrelin
– A peptide hormone released by the stomach that increases eating;
also produced by neurons in the brain.
• glucoprivation
– A dramatic fall in the level of glucose available to cells, can be
caused by a fall in the blood level of glucose or by drugs that
inhibit glucose metabolism.
• lipoprivation
– A dramatic fall in the level of fatty acids available to cells; usually
caused by drugs that inhibit fatty acid metabolism.
Brain Mechanisms
• arcuate nucleus
– A nucleus in the base of the hypothalamus that controls
secretions of the anterior pituitary gland; contains NPYsecreting neurons involved in feeding and control of
metabolism.
• paraventricular nucleus (PVN)
– A nucleus of the hypothalamus located adjacent to the
dorsal third ventricle; contains neurons involved in
control of the autonomic nervous system and the
posterior pituitary gland.
Which of the following best
describes volumetric thirst?
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When there is considerable
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When the CSF levels in the
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When you watch a movie in
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Which of the following imaging
techniques makes use of x-rays?
1. Computerized
Tomography
2. Magnetic Resonance
Imaging
3. Positron Emission
Tomography
4. Functional Magnetic
Resonance Imaging
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